Cache Assist in Hard Drives PRESENTATION TITLE GOES HERE

Transcription

1 Cache Assist in Hard Drives PRESENTATION TITLE GOES HERE

2 SNIA Forward Looking Information Disclosure Statement This SNIA presentation as part of the industry EPA ENERGYSTAR Data Center Storage Stakeholders Meeting November may include timetables, roadmaps, new technologies entering the mainstream, predictions, estimates or other information that might be considered forward-looking. While these forward-looking statements represent our current judgment on what the future holds, they are subject to risks and uncertainties that could cause actual timeframes and results to differ materially. Readers are cautioned not to place undue reliance on these forward-looking statements, which reflect our opinions and best effort planning only as of the date of this presentation. Please keep in mind that we are not obligating ourselves to revise or publicly release the results of any revision to these forward-looking statements in light of new information or future events. Throughout the discussion in the delivery of this presentation, we will attempt to present some important factors relating to the topic that may affect our estimates and predictions. 2

3 What is Cache Assist Any form of HDD caching that enhances performance without negatively impacting data integrity. Until several years ago we were here on enterprise products. Multi-segmented DRAM. Varying sizes. 128MiB not unusual Read sophistication was limited to cache and read look ahead. Writes can also utilize DRAM. Two options on how the drive informs the host of write status. Write Cache Enabled Faster Performance Risky if there is a power hiccup. Write Cache Disabled Slower Performance - No risk of data loss due to power hiccups Implication since vast majority of enterprise customers run with HDD write caching off, performance at the drive was to a large degree closely coupled to raw performance, i.e. sustained disc data rates, seek performance profiles, and RPM. 3

4 Change drivers What is the typical workload for servers by application? Takeaways: Majority of IT SW spend is on read intensive applications Read intensive applications will be challenged as the number of clients reading data increases (Integration of ERP, CRM, and OLAP) CRM: Customer Relationship Management ERP: Enterprise Resource Management (OLTP) OLAP: Data Mining & Business Intelligence CDN: Content Delivery Networks, Broadcast Office: General Office Suites Supply: Supply Chain Management VS: Video Surveillance ec: ecommerce HFT: High Frequency Trading Data Ware: Data Warehousing CM: Content Management PM: Project Management DCC: Digital Content Creation Co: Web Conferencing, Conferencing, Social Other: Other 4

5 What is Changing Starting with the appearance of 4K disc formats, NVC was used for torn write protection and read-modify-write in 512e configurations NVC for 512e TurboBoost Persistent Write Cache DRAM Read benefit Write benefit Distributed Media Cache Advanced Write Cache Improved Performance in localized workloads Write cache enabled performance with the data security of write cache disabled 5

6 Various ways to implement Cache Technology Name Seagate TurboBoost Large NAND for reads. NVC for writes HGST Distributed Media Cache Toshiba Persistent Write Cache Seagate Advanced Write Cache Physical Effect on Reads Effect on Writes Distributed caching regions on discs NOR Flash & perhaps some DMC Large size and sophistication results in greatly improve response times for localized IO None None Improved write performance. Visible in classic random writes Improved write performance. Visible in classic random writes Improved write performance. Visible in classic random writes? None Improved write performance. Visible in classic random writes 6

7 What does it all mean? Cache assist technologies can result in decoupling of performance from what might be expected given classic specs of SDR, seek time, etc The performance changes in Random Writes and HotBand can be significant. Power changes associated with performance increases might not be as expected in years past. Some technologies are separately available features, some are not Currently available read cache implementations i.e. TurboBoost, are distinct SKU s. New write caching technologies are embedded in the base product and very likely cannot be disabled. NOR based NVC sizes are frequently not specified in data sheets. Media caches have no specified size and are not spec d Small amounts of NVC on 512n drives for performance is not out of the question. Interaction of drive write caches (that cannot be disabled) with controller caches. 7

8 Hot Band and Random Results Seagate 1.8TB 10K Seagate 1.8TB 10K TurboBoost Seagate 8TB Nearline SDR Read iops Write Iops Hot Band IOPSpw Hot Band IOPS 1, , ,052.1 Hot Band Power Ran Write IOPSpw Ran Write IOPS , Ran Write Power Ran Read IOPSpw Ran Read IOPS 1, , Ran Read Power

9 Sequential Results Seagate 1.8TB 10K Seagate 1.8TB 10K TurboBoost Seagate 8TB Nearline SDR Read iops Write Iops Seq Write MiB/sec/w Seq Write MiB/sec Seq Write Power Seq Read MiB/sec/w Seq Read MiB/sec 1, , ,173.9 Seq Read Power Configuration for this and prior slide RAID 10 using 6 drives. Streaming done with 2 streams 9